1. Field of the Invention
This invention relates to a filter device for color optical scanners, especially to a filter device used in color optical scanners which can reduce the volume of the scanner system. With the employment of a new design, a tapered filter module, this invention reduces the space occupied by the filter module and the lens, resulting at a more compact scanner system.
2. Description of Prior Art
Optical scanners are a very important device for the input operation for computer systems. By using an optical scanner, image data (graphics or characters) recorded on a medium can be input to a computer system for further processing.
The theory for optical scanners is to utilize a light source which emits a light beam onto a recording medium, such as, a piece of paper. The light beam reflects from (if the medium is not a transparent medium, like paper) or penetrates through (if the medium is a transparent one, like negatives) the medium so that data representing a linear component (approximately 1/300 to 1/1000 inch in height) of the image recorded on said medium may be carried on by the light beam. The light beam later passes through a light path and reaches a lens. Dioptric image formation then is achieved by the lens and the light beam containing the recorded image data is projected to an array of linear light sensors, such as a CCD chip. The light sensor array is able to sense the illumination, or gray level, of a portion, or spot (approximately, 1/300 to 1/1,000 inch wide), of the light beam, and to transfer the illumination value into electrical signals. These signals are identical to the image components of said linear component of the scanned image and are then input onto a computer system for further processing.
The optical scanner as described above, if applied to the processing of color image, normally utilizes a "color separation device" to obtain each primary-color components of the scanned image. In other words, red, blue and green components of an image are scanned respectively and the data obtained therefrom are integrated by a computer system to form an integrated image in the computer system. In the prior art, some solutions for this purpose are proposed. Scanners using light sources which are able to emit lights of the three primary colors and scanners using color filters letting light beams of the three primary colors passing through are both the most common solutions.
Taiwan Patent Application No. 77105326 (U.S. Pat. No. 4,809,062) is an "Optical Color Line Scanning and Imaging Device Having a roller Drive". This invention relates to a color separation wheel which is positioned in front of a lens. While the wheel rotates, filters of three primary colors will pass in front the lense in turn, letting each primary-color component of the scanned image entering into the CCD and the color separation process being obtained.
Taiwan Patent Application No. 78208423 relates to a "Filter Device for Color Optical Scanners." The filters used in this 78208432 patent application line up horizontally in front of the lens and move horizontally during the scanning. The space occupied by the filter device is: EQU 170 * 20 * 30=102,000 mm.sup.3.
This 78208432 patent application serves to reduce the volume of the filter device of said No. 77105326 patent application.
Taiwan Patent Application No. 78302955 relates to a "Filter for Color Image Scanners" in which all filters are located on a fan-shaped filter frame. While the filter frame swings left and right on an axis located at the center of gravity of the frame, color separation operation is obtained. Space needed for this No. 78302955 patent is approximately: EQU 40 * 40 * 30=48,000 mm.sup.3.
Taiwan Patent Application No. 7920924 relates to a "Color Separation Mechanism for Black-and-White/Color with a rolling barrel" which installs an eight-surface Rolling Barrel with color filters on each surface. This device locates in front of a lens with at least one of its surfaces facing the lens. Color separation is achieved when the roller spins. Space needed for this filter device is: EQU 60*60*40=144,000 cm.sup.3.
Filter devices as described in the above-mentioned patents need a space larger than they actually claimed for operation. This is because that when they are in operation, an operation space is required. Nevertheless, filter devices and lenses (and image sensor array) are installed separately in these conventional devices. As a result more space is needed when the entire system is in operation.
Therefore, it has become a need for the industry to have a filter device for color optical scanners which may reduce the space occupied by the filter device and for the operation of color separation, and to reduce the size of the scanner system as a whole.
It is thus a purpose of this invention to provide a filter device for color optical scanners with a smaller volume.
An other purpose of this invention is to provide a filter device for color optical scanners that can combine the filter device with the lens used in the scanner, so as to reduce the volume of the scanner system.